Please refer to FIG. 1A which schematically shows a conventional flatbed image scanner. Generally, the image scanner 1 includes a cover (not shown) and a lower housing 10 in which a carriage module 11, a carriage-driving mechanism 12 and a circuit board 13 are disposed. The carriage module 11 is carried by a motor and gear set 121 of the carriage-driving mechanism 12 to pass under a transparent scanning platform 15 along a track 122 for proceeding a reflective or penetrative scanning for a document/picture or a film placed on the transparent scanning platform 15. When scanning, the carriage module 11 will keep electrically connecting to the circuit board 13 via a flat flexible cable (FFC) (not shown) for transmitting signals. Furthermore, when the carriage module 11 including an image pickup device moves in a scanning direction A, an image data of the scanned document is transmitted to the image pickup device via a scanning window of the carriage module 11 to be converted into a digital data. Then, the digital data is transmitted to a personal computer 3 via a transmission interface, e.g. a universal serial bus (USB) 1.1, to be further processed.
Please refer to FIG. 1B which is a diagram illustrating the carriage of the flatbed image scanner shown in FIG. 1A. For avoiding too complicated figure while describing the optical path clearly, the carriage module 11 is not proportionally enlarged herein and both the scanning platform and the scanned object are merely represented by a straight line 15. For example, a reflective scanner employs a charged-coupled device (CCD) as the image pickup device. When scanning, a light emitted from a light source 111 is reflected by the scanned document on the transparent scanning platform 15 and passes through a scanning window 115 to enter the carriage module 11. In the carriage module 11, after being reflected by a set of reflective mirrors 112 and passing through a lens 113, the light is focused on the CCD 114 for proceeding the photoelectric signal conversion. Along with the movement of the carriage module 11, the light source 111 illuminates on each of the scanning lines of the scanned document for obtaining the image data of each scanning line. In other words, when the scanning window 115 moves along with the carriage module 11 from the scanning start line B, e.g. the front end of the scanning platform 15, to the scanning end line C, e.g. the rear end of the scanning platform 15, it is necessary to have an extra space 16 at the rear end of scanning platform for accommodating optical devices 112 and 113 and the CCD 114. On the contrary, if the scanning window 115 is disposed at the rear end of the carriage module 11 as shown in FIG. 1C instead of the front end shown in FIG. 1B, an extra space 17 is also required at the front end of scanning platform for accommodating those optical devices 112 and 113 and the CCD 114. Hence, the rest area occupied by the scanner machine is redundantly larger than that required for practically scanning. Therefore, it is space-inefficient and deviating from the mini-size requirement of current computer peripheral equipments.
In addition, during the scanning period, it is necessary for the scanning window 115 of the carriage module 11 to gradually move from the scanning start line B to the scanning end line C, and transmit the realized image data into the personal computer via the transmission interface line by line to complete the entire image data of the scanned document. Therefore, the scanning speed is limited.
Therefore, the purpose of the present invention is to develop an image scanner having multiple scanning windows to deal with the above situations encountered in the prior art.